rsa 복호화 예시

package main

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/base64"
	"encoding/pem"
	"errors"
	"fmt"
	// "log"
)

var privateKey = []byte(`
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
`)

var publicKey = []byte(`
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDXQrrwRLUhFsgWw4snjemCYryE
9+RigE9v7q2/smQI7/4H9TZnrce/jm80VMxqB6c4t60HbmvuO8WspAp2oN/tZ7jx
9qSfCWJoRqI7WbgLovOvwW+hYo6orIFsc9lFG8bVRxUUCozijTmJiorKzPis/DUv
/yPObav+d1bwKzsJ9QIDAQAB
-----END PUBLIC KEY-----
`)

func main() {
	var base64Str string

	// rsa  
	// rsa     base64  
	data, err := RsaEncrypt([]byte("    |18500214038|  "))
	if err == nil {
		base64Str = base64.StdEncoding.EncodeToString(data)
		fmt.Println("      =>", base64Str)
	} else {
		fmt.Println("rsa    ", err)
	}

	// base64  
	//      rsa  
	dataStr, bErr := base64.StdEncoding.DecodeString(base64Str)
	if bErr == nil {
		origData, rErr := RsaDecrypt(dataStr)
		if rErr == nil {
			fmt.Println("      =>", string(origData))
		} else {
			fmt.Println("rsa    ：", rErr)
		}

	} else {
		fmt.Println("base64    ：", bErr)
	}

}

//   
func RsaEncrypt(origData []byte) ([]byte, error) {
	block, _ := pem.Decode(publicKey)
	if block == nil {
		return nil, errors.New("public key error")
	}
	pubInterface, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		return nil, err
	}
	pub := pubInterface.(*rsa.PublicKey)
	return rsa.EncryptPKCS1v15(rand.Reader, pub, origData)
}

//   
func RsaDecrypt(ciphertext []byte) ([]byte, error) {
	block, _ := pem.Decode(privateKey)
	if block == nil {
		return nil, errors.New("private key error!")
	}
	priv, err := x509.ParsePKCS1PrivateKey(block.Bytes)
	if err != nil {
		return nil, err
	}
	return rsa.DecryptPKCS1v15(rand.Reader, priv, ciphertext)
}